Resolving node-gyp "invalid mode: 'rU'" Error on Python 3.11

Problem Statement

When running yarn install or npm install, you encounter this error:

ValueError: invalid mode: 'rU' while trying to load binding.gyp
gyp ERR! configure error

This occurs because old versions of node-gyp (v8.x and below) use deprecated Python syntax that's incompatible with Python 3.11. When newer Python versions attempt to run the outdated node-gyp code, they reject the 'rU' file-read mode.

Common environment factors:

• macOS Ventura+ (Apple Silicon M1)
• Python ≥3.11 installed
• node-gyp <8.0.0 (or dependencies using old node-gyp)
• Node.js 16+

Recommended Solutions

1. Downgrade Python to 3.10 (Quick Fix)

Install Python 3.10 and configure your system to use it:

# Homebrew (macOS)
brew install python@3.10

# Set environment variable 
export PYTHON=/opt/homebrew/bin/python3.10  # M1 path (Intel: /usr/local/bin/python3.10)

# Verify
python --version  # Should show 3.10.x

Run your package install after setting the variable.

2. Force node-gyp Update (Best Permanent Fix)

Update node-gyp to v9.0.0+ in your project:

1. Install latest node-gyp

   npm install --save-dev node-gyp@latest

2. Force dependencies to use the updated version via package.json:

   {
     "overrides": {
       "node-gyp": "$node-gyp"
     }
   }

3. Set Compatibility Environment Variables

Point node-gyp to Python 3.10 without permanent downgrades:

export NODE_GYP_FORCE_PYTHON=/opt/homebrew/bin/python3.10

or

# One-time session override
export PYTHON=/opt/homebrew/bin/python3.10

4. Fix Node-Gyp Source Code (Fallback)

Edit input.py to remove problematic syntax:

1. Locate file:

   find node_modules -type f -name "input.py"

2. Change line:

   build_file_contents = open(build_file_path, 'rU').read()

   →

   build_file_contents = open(build_file_path, 'r').read()

Why These Solutions Work

• Python 3.10 supports rU mode, while 3.11+ does not
• New node-gyp versions (v8.0.0+) removed rU usage
• Environment variables override hardcoded paths
• Manual source edits bypass deprecated Python syntax

WARNING

Avoid system-wide Python downgrades - use version managers like pyenv for per-project control.

Verifying the Fix

After applying any solution, clear cached builds and retest:

rm -rf node_modules package-lock.json
npm cache clean --force
npm install